Hollow frangible block



Dec. 20, 1955 K. KURZ HOLLOW FRANGIBLE BLOCK Filed Aug. 15, 1950 I l-IrIL IN; 'ENTOR. KA R 1. KuR z Bai 2;, JW 5 ATTORNEYS United States PatentHOLLOW FRANGIBLE BLOCK Karl Kun, Waldsee, Wurttemberg, Germany, assignorto Siidbau, Siiddeutsche Bautechnik G. m. b. H., Waldsee, Wurttemberg,Germany Application August 15, 1950, Serial No. 179,521

Claims priority, application Germany March 13, 195i) 1 Claim. (Cl.72-41) This invention relates to a frangible building block of thehollow tile type.

Score lines in the surfaces of building blocks are well known forforming weaker sections along which the block can be broken into smallportions. Generally these score lines are placed in the thinnest portionof the tile wall to ensure a clean break at that point. Such placementof the score lines is not entirely satisfactory for blocks having amultiplicity of substantially cylindrical openings arranged in rows,with the openings in each row being staggered with respect to theopenings in adjacent rows. The walls separating the cylindrical openingsare not of uniform cross section, and a score line placed in thethinnest portion of the wall will not always cause a clean break throughthe entire block.

The object of this invention is to locate the score line with respect toan adjacent opening in the block, so that by fracturing the block alongthe score line, a clean break will be made through the block despite thefact that the openings in adjacent rows are staggered with respect toeach other. In general, this is accomplished by locating the score lineon the surface of the block and in the wall of an opening, the scoreline being laterally offset from the center of the opening a distanceequal to at least one-half the thickness of the wall separating theopening from an adjacent opening. Thus, although the score line is notat the thinnest part of the wall it lies in, it is in the plane whichcomes nearest to passing through the thinnest wall points in the wallsbetween the staggered openings in adjacent rows. A fracture started onthe score line then continues through the block substantially in thisplane to produce a clean break in the block.

The invention is described more fully with reference to the accompanyingdrawings, in which:

Figure 1 is a perspective view of the building block with the novelscore line;

Figure 2 is a cross sectional view of a detail of the block; and

Figure 3 is a cross sectional view of a detail of a modified block.

The block contains a multiplicity of cylindrical openings 12 arranged inrows, the openings in adjacent rows being staggered. Consequently, thewall 14 between the outer surface of the block and the outermostopenings is not of uniform cross section, and the same 2,727,382Patented Dec. 20, 1955 is true of the walls 16 between adjacentopenings, the walls being thinnest at the nearest point to tangencybetween the openings and the outside surface on one hand, and betweenadjacent openings on the other hand. These walls 14 and 16 are formed sothat the maximum thickness of each is less than the radius of each ofthe openings.

Score lines 18 are located in the surface of block 10 in wall 14 withinthe projected limits of hole 12. As shown in Figure 2, these score linesare positioned a distance it laterally from a line extending through thecenter of opening 12, this distance n being equal to at least one-halfthe thickness of the thinnest section of an adjacent wall 16.

A plane x passing through score lines 18 on opposite faces of block 10will then come closest to passing through the thinnest portions of thewalls 16 between the holes in adjacent rows. When the block is fracturedon line 18, the fracture will continue through the block approximatelyin plane x, a substantially clean break being obtained.

In Figure 3, block 10 is provided with additional score lines 20 locatedon the opposite side of the hole centerlines from lines 18, thusincreasing the number of sizes into which block 10 can be broken.

The invention is applicable to all forms of blocks and hollow tilehaving staggered openings, and is especially adapted to sand lime blocksin which walls 16 have a minimum thickness ranging from 3 to 25 mm.

Having described the means by which the objects of the invention areobtained, I claim:

A hollow building block comprising a body having a plurality of parallelrows of equal size substantially cylindrical openings extending throughsaid body with the openings of one row staggered and overlapped withrespect to the openings in an adjacent row, said openings beinguniformly spaced with the wall between two adjacent openings having athin portion of less thickness than the radius of each opening, a scoreline forming a fracture line located in the external surface of the bodyabove each of said openings adjacent said surface, and being laterallyOffset from a plane perpendicular to said surface and passing throughthe centerline of the adjacent opening a distance equal to at least onehalf the minimum thickness of said wall and the wall between saidsurface and the adjacent opening having having a thin portion of lessthickness than the radius of said adjacent opening.

References Cited in the file of this patent UNITED STATES PATENTS789,732 Hinton May 16, 1905 1,241,350 Dickey Sept. 25, 1917 1,566,988Simmons et al. Dec. 22, 1925 FOREIGN PATENTS 154,737 Switzerland Aug. 1,1932 155,358 Switzerland Sept. 1, 1932

